Project Summary There are 24,000 stillbirths per year in the United States, and 2.6 million stillbirths per year worldwide, with no significant decrease in the last decade. Abnormal fetal heart rhythms, such as long QT syndrome, are thought to play an important role in these deaths, and may cause 3-10% of unexplained stillbirths. This is in addition to known fetal arrhythmias, which affect 1-3% of pregnancies per year. A magnetocardiogram is the gold standard to detect these disorders, but is not portable or practical for widespread use. Other available tools such as ultrasound and cardiotocography cannot measure the intervals needed to diagnose and guide management of life threatening arrhythmias. The ideal tool for diagnosing and guiding therapy for arrhythmias is an electrocardiogram (ECG). Unfortunately, clinicians do not widely use the existing fetal electrocardiogram (fECG) devices for a variety of reasons: they do not work throughout all of gestation, can miss brief arrhythmias, have a delay between the actual rhythm and displayed rhythm, do not work in multiple gestations, and lack resolution of important intervals. Our team is developing a methodology to detect a continuous, time-resolved fECG using a novel implementation of adaptive interference cancellation (AIC). This proposal will build on our preliminary work to create a fECG clinical prototype and evaluate its performance in maternal patients at our pediatric hospital. This device is designed to generate an fECG regardless of gestational age, position, or pregnancies involving multiple fetuses. In this proposal, we aim to: 1. Transition an engineering prototype fECG to a clinical prototype by modifying the signal processing algorithm and user interface using existing datasets. 2. Measure cardiac time intervals in 16-40 week gestation fetuses and assess the reproducibility of these measurements between two readers. If successful, fetal cardiologists could use this tool to diagnose and treat known and latent fetal arrhythmias with existing anti-arrhythmic therapies. Globally, it could serve as a low cost tool to screen for arrhythmias that lead to stillbirth and to monitor fetuses for compromise during surgery, maternal medication use, and fetal interventions. Clinically implementing this critical diagnostic tool will be a landmark in the field of fetal cardiology.